Philip L. Marcus, a former engineer and teacher who became a lawyer and social activist, died Nov. 4 of bladder cancer at his home in Beaverton, Ore. The former Columbia resident was 71.

The son of Carl Marcus, an accountant, and Ida Marcus, a homemaker, Philip Leon Marcus was born in New York City and raised in the Bronx and Englewood, N.J., where he graduated from Dwight Morrow High School in 1959.

He earned his bachelor's degree in 1963 in electrical engineering from the Massachusetts Institute of Technology, and two years later, a master's degree in electrical engineering, also from MIT.

After teaching for a year at Hampton University in Hampton, Va., Mr. Marcus enrolled at the Johns Hopkins University, where he studied for a Ph.D in biophysics.

After dropping out of graduate school at Hopkins, Mr. Marcus taught chemistry and physics for three years at what is now Towson University, where he was the unofficial adviser to the campus chapter of Students for a Democratic Society.

A social activist, Mr. Marcus opposed the draft during the Vietnam War, was active in civil rights, and fought for fair housing and the end of the use of nuclear weapons.

Mr. Marcus, who did not have tenure, said in newspaper accounts that he was fired in 1969 by the university because of his political activities, which earned both him and the school the ire of then-Gov. Spiro T. Agnew.

"Then it was 1970, a time of great social ferment. One of the characteristics of the time was that lawyers were using the courts to help people, protecting constitutional rights, and securing equal treatment for the disadvantaged," Mr. Marcus wrote in a profile. "It was a profession in which one could do good, and I believed I had a talent for the law."

Changing careers, Mr. Marcus earned a degree in 1973 from the University of Maryland School of Law.

"I did six years of private practice, highlighted by getting the Supreme Court to order Texas to put my client Gene McCarthy on the presidential ballot in 1976," Mr. Marcus wrote in another biographical profile for MIT.

"At the point of another suit, I got the Baltimore Orioles to create 'transfer' seating for a paraplegic client so he could watch the 1979 American League Champion Series and the World Series. I then prosecuted discrimination cases with a state agency for six years," he wrote.

In 1989, he established Training To Go, which focused on software training, and then a second company, TTG Services, which specialized in software development.

In 1983, Mr. Marcus fell under the spell of personal computers. "Bored by law cases taking up to 15 years to close," he wrote, he decided to enter the personal computer industry.

A former client who was the CEO of a PC maker hired him, and from 1985 to 2005, he worked in various phases of the industry, mainly developing database applications.

"Eventually I burned out and reactivated my law license," he wrote.

He began working in patent licensing and later focused his practice on copyrights and trademarks.

Mr. Marcus then founded Negotiation Pro and Your Small Business Owner that assisted businessmen in dealing with opportunities and disputes that arose in business.

Mr. Marcus was the author of "Zen and the Art of Negotiation: Successful Negotiation for People Who Hate to Negotiate."

Before moving to Columbia in 2000, Mr. Marcus was a longtime Charles Village resident and had been a member of the Charles Village Association. He later served two terms as a member of Columbia's King Contrivance Village Community Association board, and later as a board member of the Columbia Association from 2004 to 2008.

While living in Ellicott City in the 1990s, Mr. Marcus was ticketed in 1996 for having a "For Sale" sign on his car that he parked alongside a road, which was in violation of a county ordinance.

Mr. Marcus took his case to Howard County District Court and after successfully convincing Judge R. Russell Sadler that his First Amendment rights were being violated, the judge ruled the ordinance unconstitutional and relieved him of the $48 tickets.

"For Marcus, it is a matter of free speech and common sense. He notes that he could hang a dead chicken from his radio antenna or put up a sign that says 'Bob Dole is a Fink' or paint his car in 1960s psychedelic colors and still qualify as a law-abiding citizen," reported The Washington Post.

"I'm not on a big campaign to shut down the government. My campaign is to get rid of one opprobrious law," Mr. Marcus told the newspaper.

Mr. Marcus, who was a member of the American Civil Liberties Union, was a prolific contributor of hundreds of letters to the editors of newspapers. He also remained actively involved with MIT.

In 2011, Mr. Marcus and his wife, Peg Silloway, moved to Beaverton.

"I got tired of the extreme weather in Maryland, and the zoo of the I-95 corridor. We lit out for Portland, Oregon," Mr. Marcus wrote in his biographical notes. "We love the temperate climate and the great soil where anything grows. We love the laid back people and the wildly varied geology and geography that makes for wonderful traveling and photography."

Services were private.

In addition to his wife, Mr. Marcus is survived by a son, Gary Marcus of New York City; a daughter, Julie Marsden of Ellicott City; and a grandson. Earlier marriages to the former Marilyn "Molly" Purpel and Linda Marsden ended in divorce.